Washington ? New border-crossing rules that take effect in two weeks will mean longer lines and stiffer demands for ID, including for returning Americans, Homeland Security Secretary Michael Chertoff said Thursday.

A driver’s license won’t be good enough to get Americans past a checkpoint at the Canadian or Mexican border, Chertoff said. That will be a surprise to many people who routinely cross the border with Canada, but Chertoff bristled at criticism that such extra security would be inconvenient. More than 800,000 people enter the U.S. through land and sea ports each day.

“It’s time to grow up and recognize that if we’re serious about this threat, we’ve got to take reasonable, measured but nevertheless determined steps to getting better security,” he said in an interview with The Associated Press.

Thousands of people° enter the U.S. through land crossings every day. The biggest effect of the change will be at the Canadian border because it applies to Canadians and Americans. Non-Americans coming in through Mexico already need extra documentation.

Congressional critics representing Northern border states were anything but impressed with Chertoff’s rhetoric.

His department has proved incapable of implementing a 2004 law on border security, and Chertoff “frankly has as much credibility on telling people to ‘grow up’ as Geoffrey the Giraffe,” said Rep. Tom Reynolds, R-N.Y.

Added Sen. Norm Coleman, R-Minn., “Secretary Chertoff’s comments that those objecting to the plan need to ‘grow up’ indicates that the department still doesn’t understand the practical effects of DHS policies on the everyday lives of border community residents.”

Sen. Patrick Leahy, Democratic chairman of the Senate Judiciary Committee, said the move does nothing to enhance security and will only hurt the economy. “When it comes to the northern border, the muddled thinking and poor planning at DHS seems to have no bounds, and the agency that botched Katrina seems to have no shame and no memory to boot,” Leahy said.

Under the new system, which takes effect Jan. 31, Americans and Canadians who are 19 or older will have to present proof of citizenship when they seek to enter the United States through a land or sea port of entry.

A passport will be fine. Or a birth certificate coupled with some other ID such as a driver’s license.

For people other than Americans or Canadians, the rules at the northern border will be unchanged – passports and visas will still be required. The same goes for non-Americans at the Mexican border.

Chertoff said longer lines at the border at first are inevitable. “Until people get the message, there will be some delays,” he said. He predicted that would change once people got used to the new system, and he said border agents would be flexible in applying the new rules at the beginning.

Not moving to the new restrictions would be a tragic mistake, Chertoff said. “I can guarantee if we don’t make this change, eventually there will come a time when someone will come across the border exploiting the vulnerabilities in the system and some bad stuff will happen. And then there’ll be another 9/11 commission and we’ll have people come saying ‘Why didn’t we do this?'”